1. Field of the Invention
The present invention relates to a method and an apparatus for recording and/or reproducing data, and more particularly, to a method and an apparatus for recording and/or reproducing data in which a recording and/or reproduction velocity can be reduced when a data recording and/or reproduction error occurs due to a defect of an optical disc during recording of data on and/or reproduction of data from the optical disc.
2. Description of the Related Art
Writable optical discs may deflect light, be eccentric, or be scratched during the manufacturing process. Such deflections, eccentricities, and scratches are referred to as defects. Recording of data on optical discs containing defects may fail or be of poor quality due to the defects. In particular, high-speed data recording on optical disks is greatly affected by the defects.
An algorithm has been developed to reduce the recording velocity so as to prevent recording quality from deteriorating during high-speed recording of data on optical discs due to the defects of the optical discs. The algorithm is used to record data on and/or reproduce data from optical discs.
FIG. 1 is a graph showing a conventional partial constant linear velocity (PCLV) algorithm used to reduce a recording velocity. The conventional PCLV algorithm lowers the rotation velocity of an optical disc to a constant linear velocity (CLV) when a recording error occurs during the recording of data on the optical disc that is rotating at a specific constant angular velocity (CAV).
The conventional PCLV algorithm will be explained in more detail with reference to FIG. 1. In a normal mode, data is recorded at a CAV of 52×. As can be seen in FIG. 1, “A” indicates a case where a recording velocity is lowered prior to reaching 32× due to a recording error. Here, the recording velocity is set to a CLV of 24× to complete recording of data.
“B” indicates a case where a recording error occurs before the recording velocity reaches 40× and the recording velocity is lowered to a CLV of 32× to complete recording of data.
“C” indicates a case where the recording error occurs before the recording velocity reaches 48× and the recording velocity is lowered to a CLV of 40× to complete recording of data.
When the recording error re-occurs in spite of lowering of the recording velocity once, the recording velocity is again lowered to a lower CLV.
FIG. 2 is a graph showing variations in recording velocity and rotations per minute (RPM) when the conventional PCLV algorithm is used. Referring to FIG. 2, the recording velocity is lowered to a CLV of 16× during recording of data at a CAV of 52×. The RPM decreases from 10K to about 3.7K resulting in a difference of about 6.3K.
In the PCLV algorithm, the apparatus may have unstable operations due to sharp variations in the recording velocity and the RPM, or the apparatus may take a long time to record and/or reproduce data. Unstable operation of the apparatus indicates that a problem occurs when a phase lock loop (PLL) is locked, data is overwritten, or recording of data fails due to an unstable servo.